Quantitative assessments of ultrasound‐based rotator cuff muscle quality

Abstract Background Fatty infiltration and muscle atrophy strongly influence clinical outcomes in patients with rotator cuff tears. Emerging quantitative techniques integrated with brightness‐mode ultrasound and shear wave elastography (SWE) have been used to evaluate soft tissue morphology and mechanical properties. Objective To evaluate integrative B‐mode ultrasound and SWE as a potential tool to quantify rotator cuff muscle quality. Methods Twenty participants (a total of 32 shoulders) with and without rotator cuff tears were included in this study. Shear wave speed (SWS) was measured in SWE‐mode and cross‐sectional area (CSA) was measured in B‐mode with a linear transducer. Muscle strength was measured using a hand‐held dynamometer. Psychometric properties were calculated for SWS and CSA under both passive and active conditions. Results The SE of measurement and minimum detectable difference for the SWS of supraspinatus in shoulders with rotator cuff tears were 0.195 and 0.541 m/s, respectively. The SE of measurement and minimum detectable difference for the CSA of supraspinatus in shoulders with rotator cuff tears were 0.265 and 0.733 cm 2 , respectively. Correlation analysis between passive mean SWS and CSA revealed a strong correlation (r = 0.652, p = .003) for the supraspinatus. Conclusion These findings demonstrate a strong positive correlation between SWS and CSA of the supraspinatus in participants with rotator cuff tears but not the infraspinatus or in asymptomatic participants. Assessment of SWS and CSA under passive conditions yields superior psychometric properties compared to active conditions. However, the lack of association between SWS and strength limits the clinical utility of SWE to quantify rotator cuff muscle quality.